/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.validation;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;

/**
 * Utility class offering convenient methods for invoking a {@link Validator}
 * and for rejecting empty fields.
 *
 * <p>Checks for an empty field in {@code Validator} implementations can become
 * one-liners when using {@link #rejectIfEmpty} or {@link #rejectIfEmptyOrWhitespace}.
 *
 * @author Juergen Hoeller
 * @author Dmitriy Kopylenko
 * @see Validator
 * @see Errors
 * @since 06.05.2003
 */
public abstract class ValidationUtils {

    private static final Log logger = LogFactory.getLog(ValidationUtils.class);


    /**
     * Invoke the given {@link Validator} for the supplied object and
     * {@link Errors} instance.
     *
     * @param validator the {@code Validator} to be invoked
     * @param target    the object to bind the parameters to
     * @param errors    the {@link Errors} instance that should store the errors
     * @throws IllegalArgumentException if either of the {@code Validator} or {@code Errors}
     *                                  arguments is {@code null}, or if the supplied {@code Validator} does not
     *                                  {@link Validator#supports(Class) support} the validation of the supplied object's type
     */
    public static void invokeValidator(Validator validator, Object target, Errors errors) {
        invokeValidator(validator, target, errors, (Object[]) null);
    }

    /**
     * Invoke the given {@link Validator}/{@link SmartValidator} for the supplied object and
     * {@link Errors} instance.
     *
     * @param validator       the {@code Validator} to be invoked
     * @param target          the object to bind the parameters to
     * @param errors          the {@link Errors} instance that should store the errors
     * @param validationHints one or more hint objects to be passed to the validation engine
     * @throws IllegalArgumentException if either of the {@code Validator} or {@code Errors}
     *                                  arguments is {@code null}, or if the supplied {@code Validator} does not
     *                                  {@link Validator#supports(Class) support} the validation of the supplied object's type
     */
    public static void invokeValidator(
            Validator validator, Object target, Errors errors, @Nullable Object... validationHints) {

        Assert.notNull(validator, "Validator must not be null");
        Assert.notNull(target, "Target object must not be null");
        Assert.notNull(errors, "Errors object must not be null");

        if (logger.isDebugEnabled()) {
            logger.debug("Invoking validator [" + validator + "]");
        }
        if (!validator.supports(target.getClass())) {
            throw new IllegalArgumentException(
                    "Validator [" + validator.getClass() + "] does not support [" + target.getClass() + "]");
        }

        if (!ObjectUtils.isEmpty(validationHints) && validator instanceof SmartValidator) {
            ((SmartValidator) validator).validate(target, errors, validationHints);
        }
        else {
            validator.validate(target, errors);
        }

        if (logger.isDebugEnabled()) {
            if (errors.hasErrors()) {
                logger.debug("Validator found " + errors.getErrorCount() + " errors");
            }
            else {
                logger.debug("Validator found no errors");
            }
        }
    }


    /**
     * Reject the given field with the given error code if the value is empty.
     * <p>An 'empty' value in this context means either {@code null} or
     * the empty string "".
     * <p>The object whose field is being validated does not need to be passed
     * in because the {@link Errors} instance can resolve field values by itself
     * (it will usually hold an internal reference to the target object).
     *
     * @param errors    the {@code Errors} instance to register errors on
     * @param field     the field name to check
     * @param errorCode the error code, interpretable as message key
     */
    public static void rejectIfEmpty(Errors errors, String field, String errorCode) {
        rejectIfEmpty(errors, field, errorCode, null, null);
    }

    /**
     * Reject the given field with the given error code and default message
     * if the value is empty.
     * <p>An 'empty' value in this context means either {@code null} or
     * the empty string "".
     * <p>The object whose field is being validated does not need to be passed
     * in because the {@link Errors} instance can resolve field values by itself
     * (it will usually hold an internal reference to the target object).
     *
     * @param errors         the {@code Errors} instance to register errors on
     * @param field          the field name to check
     * @param errorCode      error code, interpretable as message key
     * @param defaultMessage fallback default message
     */
    public static void rejectIfEmpty(Errors errors, String field, String errorCode, String defaultMessage) {
        rejectIfEmpty(errors, field, errorCode, null, defaultMessage);
    }

    /**
     * Reject the given field with the given error code and error arguments
     * if the value is empty.
     * <p>An 'empty' value in this context means either {@code null} or
     * the empty string "".
     * <p>The object whose field is being validated does not need to be passed
     * in because the {@link Errors} instance can resolve field values by itself
     * (it will usually hold an internal reference to the target object).
     *
     * @param errors    the {@code Errors} instance to register errors on
     * @param field     the field name to check
     * @param errorCode the error code, interpretable as message key
     * @param errorArgs the error arguments, for argument binding via MessageFormat
     *                  (can be {@code null})
     */
    public static void rejectIfEmpty(Errors errors, String field, String errorCode, Object[] errorArgs) {
        rejectIfEmpty(errors, field, errorCode, errorArgs, null);
    }

    /**
     * Reject the given field with the given error code, error arguments
     * and default message if the value is empty.
     * <p>An 'empty' value in this context means either {@code null} or
     * the empty string "".
     * <p>The object whose field is being validated does not need to be passed
     * in because the {@link Errors} instance can resolve field values by itself
     * (it will usually hold an internal reference to the target object).
     *
     * @param errors         the {@code Errors} instance to register errors on
     * @param field          the field name to check
     * @param errorCode      the error code, interpretable as message key
     * @param errorArgs      the error arguments, for argument binding via MessageFormat
     *                       (can be {@code null})
     * @param defaultMessage fallback default message
     */
    public static void rejectIfEmpty(Errors errors, String field, String errorCode,
                                     @Nullable Object[] errorArgs, @Nullable String defaultMessage) {

        Assert.notNull(errors, "Errors object must not be null");
        Object value = errors.getFieldValue(field);
        if (value == null || !StringUtils.hasLength(value.toString())) {
            errors.rejectValue(field, errorCode, errorArgs, defaultMessage);
        }
    }

    /**
     * Reject the given field with the given error code if the value is empty
     * or just contains whitespace.
     * <p>An 'empty' value in this context means either {@code null},
     * the empty string "", or consisting wholly of whitespace.
     * <p>The object whose field is being validated does not need to be passed
     * in because the {@link Errors} instance can resolve field values by itself
     * (it will usually hold an internal reference to the target object).
     *
     * @param errors    the {@code Errors} instance to register errors on
     * @param field     the field name to check
     * @param errorCode the error code, interpretable as message key
     */
    public static void rejectIfEmptyOrWhitespace(Errors errors, String field, String errorCode) {
        rejectIfEmptyOrWhitespace(errors, field, errorCode, null, null);
    }

    /**
     * Reject the given field with the given error code and default message
     * if the value is empty or just contains whitespace.
     * <p>An 'empty' value in this context means either {@code null},
     * the empty string "", or consisting wholly of whitespace.
     * <p>The object whose field is being validated does not need to be passed
     * in because the {@link Errors} instance can resolve field values by itself
     * (it will usually hold an internal reference to the target object).
     *
     * @param errors         the {@code Errors} instance to register errors on
     * @param field          the field name to check
     * @param errorCode      the error code, interpretable as message key
     * @param defaultMessage fallback default message
     */
    public static void rejectIfEmptyOrWhitespace(
            Errors errors, String field, String errorCode, String defaultMessage) {

        rejectIfEmptyOrWhitespace(errors, field, errorCode, null, defaultMessage);
    }

    /**
     * Reject the given field with the given error code and error arguments
     * if the value is empty or just contains whitespace.
     * <p>An 'empty' value in this context means either {@code null},
     * the empty string "", or consisting wholly of whitespace.
     * <p>The object whose field is being validated does not need to be passed
     * in because the {@link Errors} instance can resolve field values by itself
     * (it will usually hold an internal reference to the target object).
     *
     * @param errors    the {@code Errors} instance to register errors on
     * @param field     the field name to check
     * @param errorCode the error code, interpretable as message key
     * @param errorArgs the error arguments, for argument binding via MessageFormat
     *                  (can be {@code null})
     */
    public static void rejectIfEmptyOrWhitespace(
            Errors errors, String field, String errorCode, @Nullable Object[] errorArgs) {

        rejectIfEmptyOrWhitespace(errors, field, errorCode, errorArgs, null);
    }

    /**
     * Reject the given field with the given error code, error arguments
     * and default message if the value is empty or just contains whitespace.
     * <p>An 'empty' value in this context means either {@code null},
     * the empty string "", or consisting wholly of whitespace.
     * <p>The object whose field is being validated does not need to be passed
     * in because the {@link Errors} instance can resolve field values by itself
     * (it will usually hold an internal reference to the target object).
     *
     * @param errors         the {@code Errors} instance to register errors on
     * @param field          the field name to check
     * @param errorCode      the error code, interpretable as message key
     * @param errorArgs      the error arguments, for argument binding via MessageFormat
     *                       (can be {@code null})
     * @param defaultMessage fallback default message
     */
    public static void rejectIfEmptyOrWhitespace(
            Errors errors, String field, String errorCode, @Nullable Object[] errorArgs, @Nullable String defaultMessage) {

        Assert.notNull(errors, "Errors object must not be null");
        Object value = errors.getFieldValue(field);
        if (value == null || !StringUtils.hasText(value.toString())) {
            errors.rejectValue(field, errorCode, errorArgs, defaultMessage);
        }
    }

}
